(1) Field of Invention
The present invention relates to a circuit for sensing input conditions of a keyboard. Particularly, the circuit monitors appropriate signals through a regulated slot and performs a power-saving function in a PC on condition that there are no commands being inputted from a keyboard.
(2) Description of the Prior Art
A logic device which can generate a power cut-off signal to operate the power-saving system has been used in the prior art PC. This logic device was used to generate a signal needed for power-saving when the input function remained unused for a predetermined time. In other words, when there is no interrupt request on any of lines IRQ3, IRQ4, IRQ6, IRQ7, IRQ12, IRQ14 showing the input conditions of each input means through its dedicated slot for a predetermined period, the conventional logic device or controller generates a power-saving signal.
The logic device circuit for sensing input conditions of keyboard which was used for performing power saving function in prior art PC, however, had some disadvantages. In particular, this circuit could be operated only by means of an interrupt request line, the representative input means for which exists in the motherboard itself. Consequently, this circuit can be implemented only by fabricating or modifying the motherboard itself.